Adrenoceptor Antagonists: Pharmacological Actions and Uses
Blood vessel dilation, hypotension, and reflex tachycardia resulting from adrenoceptor antagonists can have therapeutic benefits for conditions like hypertensive crisis, pheochromocytoma, and peripheral vascular disease. Newer drugs offer improved selectivity and reduced side effects compared to older non-selective medications.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
You are allowed to download the files provided on this website for personal or commercial use, subject to the condition that they are used lawfully. All files are the property of their respective owners.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author.
E N D
Presentation Transcript
ADRENOCEPTOR ANTAGONISTS Phenoxybenzamine, Phentolamine, Tolazoline, Ergotamine, DHE, Ergotoxine Yohimbine( 2) Non-selective older drugs; Block both 1 & 2 Prominent venodilation.
PHARMACOLOGICAL ACTIONS 1) Blood Vessels:- Severe dilation all over body. in t.p.r. and venous return Marked hypotension (+Postural hypot. also) Reflex tachycardia d/t uninhibited release of NA act on 1.
PHARMACOLOGICAL ACTIONS (contd.) 2) Kidney:- blood flow to kidneys Reflex in secretion of renin Activation of R-A-A system retention of Na/ water blood volume Drawbacks in Ttof HT:- Intense vasodilation Sym. Outflow Cardiac stimulation (palpitation), Miosis, Diarr Postural hypo, Nasal block, Impotence in male
NEWER DRUGS - Prazosin (a>v.), Doxazosin, Terazosin, Alfuzosin - Selective 1 block only No marked S/E - First dose effect is +. - BP is - less severe - Tamsulosin:- Most recent drug ( 1A, 1D ) On prostate only - BHP
THERAPEUTIC USES Hypertensive crisis Pheochromocytoma Peripheral vascular disease BHP (newer selective drugs)
-ADRENOCEPTOR ANTAGONISTS I. Non-selective:- Propranolol, Timolol, Labetalol ( also), Pindolol (Sym. mim.), Carvedilol (antioxidant). II. Cardio-selective:- Metoprolol, Atenolol, Betaxolol ( also), Celiprolol ( 2 agonist)
PHARMACOLOGICAL ACTIONS 1) CVS:- A) Heart- in rate & force in cardiac work & O2 consumption Propanolol has Mem. Stabilizing action also. B) Bl. Vessels- Initially mild in PR. Later - in CO circulating volume V PR Ultimately in BP Sys./ Dias. (in HT mainly)
PHARMACOLOGICAL ACTIONS(contd.) 2) CNS:- Non specific R in vasomotor area in sym. outflow. (Atenolol, Sotalol) 3) PNS:- Presynaptic 2 R at post gang. Sym. neuron terminals in release of NA.
PHARMACOLOGICAL ACTIONS(contd.) 4) Kidney:- 1 R at JG cells in release of renin activity in R-A-A system. NOTE:- All the above 4 action contribute. 5) Respiratory sys:- 2 in bronchi blocked bronchospasm (esp. Asthmatics)
PHARMACOLOGICAL ACTIONS (contd.) 6) Metabolic:- 2 in liver/ muscle cells Block in glycogenolysis. 7) Skeletal Muscles:- Presynaptic 2 at LMN release of ACh Blood flow to muscles fatigue 8) Eye:- secretion of aqueous.
ADVERSE EFFECTS & CONTRAINDICATIONS CHF may be precipitated, Sick sinus syndrome Muscular weakness, fatigue Bronchial asthma may be precipitated, COPD Partial or complete heart block Peripheral vascular disease worsened. Cold hands & feet. Sudden withdrawal HT crisis Not in Diabetics
THERAPEUTIC USES Hypertension Angina Pectoris Improve O2 supply/demand ratio Cardiac arrhythmias- Propranolol CHF Myocardial Infarction- Secondary prophylaxis O2 consumption Prevention of arrhythmias Thyrotoxicosis
THERAPEUTIC USES(contd.) Essential tremors Anxiety Glaucoma Drops/ ocuserts Pheochromocytoma - along with blocker Migraine
